Portable screen



FIG. 1 is a front isometric view showing the design;

FIG. 2 is a front view showing the design;

FIG. 3 is a back view showing the design;

FIG. 4 is a right side view showing the design;

FIG. 5 is a left side view showing the design;

FIG. 6 is a top view showing the design; and,

FIG. 7 is a bottom view showing the design. 

CLAIM The ornamental design for a portable screen, as shown. 